A Fatal Vow
by The Lost Samurai
Summary: The first time Zuko set foot in the Western Air Temple, his redemption was everything to him. By the time he returned there, he knew, looking back, that it had almost been his undoing. Nevertheless, this time, he vowed that he would truly redeem himself, no matter what it took. And thus, he was undone. Book Three AU. Oneshot. I don't own Avatar: The Last Airbender.


Summary: The first time Zuko set foot in the Western Air Temple, his redemption was everything to him. By the time he returned there, he knew, looking back, that it had almost been his undoing. Nevertheless, this time, he vowed that he would truly redeem himself, no matter what it took. And thus, he was undone. Book Three AU. Oneshot.

* * *

Part I: Verbal Warfare

If there was one good lesson he ever learned from the psychopathic side of his family, it was how to take a beating. Both Ozai and Azula had imparted valuable knowledge to him in this regard, whether unwittingly or not.

Take Ozai, for example. The first time his father had tried to mutilate him, he'd succeeded. Zuko had the scar to prove it. But the second time? He'd caught the bolt of lightning aimed at his heart and thrown it right back.

Zuko liked to think there was some improvement there.

Azula, on the other hand, had always tested the limits of his pain tolerance in much subtler ways. Usually. There were also numerous occasions when she'd shot blue fire at him with extreme prejudice, but if there was one thing he had learned to fear from her, it surprisingly wasn't her prodigious firebending, but her silver tongue.

Azula had always been very good at making Zuko throw away his own happiness without even realizing what he was doing with naught but a few words. This was a much harder tactic to counter. At least fire and lightning were predictable. Don't let either hit you; it'll fucking hurt. But verbal assaults? They were different. You never knew which angle they'd strike you from. They could ruin one's entire life without them ever being the wiser.

He was ashamed to say he'd never truly grown out of his ignorance to the art of verbal warfare until after Ba Sing Se. Azula had caused him to forsake everything he stood for with a few choice words. She'd played at his pride and his insecurities, turning both against him, and watched as his life fell apart, just as she had when they were kids. Zuko didn't think he'd ever meet someone who could make him cause as much damage to his own life as she could with words alone.

The day he did just that he was, fittingly enough, attempting to redeem himself.

Tensions were high for the first couple weeks he'd spent in the Western Air Temple. Even after Zuko and Aang had returned from the Sun Warrior's Temple, Avatar completely unscathed mind you, it was really only Aang and Toph that trusted him. Aang, because they'd had their journey together, and Toph, well, because she could catch him in a lie as it escaped his mouth. Sokka still regarded him with wariness, but was willing to put aside his suspicion for the sake of cooperating as a group.

Katara, on the other hand? She hated his guts, and would make scathing remarks at the slightest provocation, or more often, with no provocation at all. It was one such instance, on the morning after he returned from the temple of the Sun Warriors, that the art of verbal warfare reared its nauseating head.

"I can help with breakfast, if you'd like." It was an innocent offer. He really just wanted to be helpful. Katara didn't see it that way.

"Oh, His Royal Highness it deigning to partake in _peasant_ work? Do you even _know_ how to cook?"

Zuko thought that was a bit unfair. He'd survived in the wilderness for weeks at a time when he'd been alone in the Earth Kingdom, and had been forced to hunt for game, with some degree of success. He wasn't a gourmet chef by any stretch of the imagination, but he wasn't completely incompetent when it came to food.

"Just simple stuff. I can add spices, light the fire, and slow heat whatever you're cooking with my firebending," he replied, not rising to the jab.

"I'd rather not have _burnt_ breakfast."

"I'm not going to burn it! I just wanted to know if you needed help."

"Oh, _now_ you want to help?"

The other members of the group who had already risen suddenly grew quiet as they observed the exchange. It was obvious this wasn't about breakfast anymore.

Zuko knew what she was referring to. He'd never forget. But why did this have to come up now, when all he'd been trying to do was help cook?

"I wouldn't be here if I didn't," he replied, his quiet voice gaining a steel edge.

"Then I think I'd like it better if you _didn't_." The girl didn't miss a beat, even as the rest of the group looked like they wanted to intervene.

Zuko sighed, and it came out tired and bitter. "I get that you can't stand me, but you _know_ why I have to be here."

"Yes, I know. To teach Aang firebending. And that's _all_ you're here for, so don't get familiar!"

Aang looked like he wanted to protest, but Toph beat him to it. "Enough, Katara," the earthbender said, uncharacteristically stern.

Katara turned to her, indignant. " _What_?" she snapped.

"I said can it, Ice Queen. We all agreed to let Zuko into the group, but ever since he joined you've been nothing but spiteful."

"Why _wouldn't_ I be spiteful? Do you even know what he—"

"Toph's right Katara," Sokka interrupted. "I'm not saying you have to like the guy right away, but at the very least get along. Zuko isn't trying to start something, so stop provoking him."

"Of course is isn't trying to start something!" the waterbender shot back. "He knows full what would happen if—"

"Dammit, Katara!" Zuko shouted, causing everyone to jump. The visit she'd paid him the night he'd arrived here flashed through his mind as a result of her words, enraging him. "What do you _want_ from me? I know you don't give a rat-viper's ass, but I'm trying here! So just tell me what you _want from me_!"

"You really want to know!?" Katara shouted, turning back to him with a scathing glare.

"Yes! Just tell me and I'll do it!"

"I want you to leave! I don't want to have to see your face again!" she screeched, much to Aang's growing horror.

"Katara, stop! This isn't like you!"

"Put a sock in it Ice Queen, before this goes too far!" Toph snapped.

"Wait." The single word silenced their protests, and they turned to Zuko, half expecting him to blow his stack. His eyes were narrowed as he regarded Katara with a morbid curiosity.

"Is that really what you want?" he asked quietly, much to everyone's shock.

"Yes!" Katara snapped, losing her patience.

"Katara, _shut up!_ "

"I already promised to teach Aang firebending. You know I can't go back on that, right?" Zuko's voice was clipped, revealing nothing of his inner thoughts.

"Fine then, after," Katara shrugged. She had worked herself into a fit, and she wasn't stopping now. "You said you wanted to help us restore balance? Well, after Sozin's Comet comes, your job will officially be _over_ , assuming you haven't betrayed us by then!" she spat. "So after that, leave and don't show your face in front of me again!"

The group was stunned into silence.

"Do you know what you're asking of me?" Zuko's voice exuded a quiet rage. His entire body was tensed like a man about to jump to his death.

"What? Not so eager now? You asked what I wanted, so there you go," Katara said coldly. "You're big on honor, right? Swear on whatever scraps of it you have left after what you did."

Aang was pale.

Zuko's body relaxed, as if all the tension had just drained out of him, but if the airbender had to relate the simple action to something, it would be a plant shriveling up and dying from lack of sun.

He looked Katara dead in the eyes. Toph's own eyes were filled with tears before he even spoke.

"I give you my word. On my honor," he said. Then he got up and walked away without another word.

Katara scoffed, clearly not believing him. Toph screamed in fury, and Katara was mercilessly knocked to the ground by the punishing earth.

"Ugh! Toph!" she protested, but the girl just stormed off. Why was it always her? Why did she, the blind one, have to be the only one who could fucking _see_?

Sokka sighed. "That was way too much drama this early in the morning," he groaned.

"Sokka...this is really, really not good," Aang said weakly.

"I wouldn't worry too much, Aang," Sokka said. "Katara won't hold him to that promise. She's just angry. By the time Sozin's Comet arrives, she'll come around."

Aang tried to calm down. That was probably true. Katara would cool down eventually and tell Zuko he didn't need to keep that stupid promise. So why did he feel like something very, very bad had just happened?

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Part II: On His Honor

Katara and Zuko were quiet and somber as they rode upon Appa's back. The confrontation with Yon Rha weighed heavily on Katara's mind. She still didn't know whether she'd made the right choice, but she was willing to focus on other things for now. She had to move on from this...anger.

"Zuko," she whispered, drawing the firebender out of his thoughts. He'd been quiet, these past few weeks, even more so than usual. Even after he'd returned with Sokka from the Boiling Rock with a war blimp full of freed prisoners, he'd been unusually solemn. Katara couldn't help but think it was due to the argument they'd had before, and she winced in guilt as she remembered the promise.

"What is it?"

"...Thank you for doing this. It meant a lot to me."

"You're welcome."

"And...remember that promise you made? Well, you don't really have to keep it."

He was silent. Katara's brow furrowed in worry. Was he still mad about what she said that day?

"Seriously, I'm sorry I told you to make that stupid promise."

He kept his silence for a moment, before finally replying. "So am I."

Katara sighed. "But like I said, you don't have to keep it. You're not still angry, are you?"

Zuko turned to her, and Katara was startled. He didn't look angry. All she could see on his face was a deep longing, and an unfathomable pain.

"I gave my word, Katara. On my _honor_."

Katara stared uncomprehendingly for a moment, before her eyes widened in a deep, chilling, horror.

"Oh no."

A few choice words could tear someone's life apart around them. Zuko had learned that lesson well. But he'd never meant to pass it on.

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A/N: And there it is, my first oneshot! I don't know where this came from really, the idea just popped into my head and I sat down to write it. Tell me what you thought. Good? Bad? Believable? Not so much? Post a review and let me know!

Lost out.


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